RU2578725C1 - Method for producing heat and fuel gas from finely dispersed fuel (organic) by burning or pyrolysis thereof using fluidised regenerative cells - Google Patents

Abstract

FIELD: energy.

SUBSTANCE: invention relates to heat engineering and can be used in municipal engineering, metallurgy, construction and other industries and is aimed at solution to direct incineration and gasification of fine organic substances, i.e. converting organic part of solid fuel in combustible gases at high-temperature heating with oxidising agent. Method consists in that combustion of fine organic fuel is carried out in cylindrical lined chamber, lower part of which is sand layer, on which one layer of discrete particles is scattered, which are regenerative elements. Fuel is fed uniformly on combustion mirror, oxidant (air) is supplied through rotating manifolds fixed on central axis in layer between sand and discrete particles, fluidization of discrete particles is provided by rotating manifolds. Transition from mode of complete fuel combustion to gas generation mode is performed by varying air supply, maintaining temperature at combustion mirror below ash melting temperature, obtained gas is after burned in upper part of chamber, more complete burning out of fuel carbon in gas generation mode provides maintenance of required moisture content of initial fuel.

EFFECT: possibility to use different types of solid fuel (peat, combustible shale, coal, wastes from production, et cetera) for producing heat and combustible gas.

1 cl, 2 dwg

Description

The invention relates to a power system and can be used in utilities, metallurgy, construction and other industries.

Full or partial (gas generation) combustion of fine fuel is widely used in everyday practice, and for its implementation it is always necessary to ensure a sufficiently long flight of particles in the surrounding gas phase, whether in combustion processes in flare and cyclone furnaces or in fluidized-bed furnaces (see ., for example, Heat power plants and heat supply: a textbook for technical colleges / Z.F. Nemtsev, G.V. Arseniev. - Moscow: Energoizdat, 1982. - 400 pp., ill. - For university students. P. 225) .

From patent RU 2184317, publ. 06/27/2002, we have chosen as the closest analogue (prototype), we know a device for burning solid fuel, which contains a vertical cylindrical combustion chamber with a feeder in the form of a pneumomechanical spreader and a flue gas outlet pipe in the upper part and in the lower part with a bunch of perforated horizontal pipes with a plugged end, rigidly fixed in a gas distribution manifold and immersed in an inert filling of a fraction of 0.1-2.0 mm. The gas-distributing manifold is installed coaxially with the chamber walls and consists of two parts: a fixed one connected to the bottom and a movable one mounted for rotation on the output shaft of the drive. The pipes are placed radially on the moving part of the collector, and their perforation is made one-sided, coinciding with the direction of movement of the shaft. A layer of coarse refractory material with a particle size of 20.0-50.0 mm is located above the inert filling, over which an overflow threshold is made in the side wall of the chamber, connected to a container for collecting excess inert filling. The advantage of this device is that various types of solid fuel can be used, but the device is designed to completely burn fuel. The disadvantages include the fact that a number of types of solid fuels, such as brown coal and some types of coal, husks of cereals, peat, etc., have a low melting point of ash of about 950-1050 ° C and when everything necessary for complete combustion is supplied of air fuel to the collectors, the temperature at the combustion mirror is exceeded above the melting temperature of the ash, which will lead to the failure of the entire combustion organization system due to slagging of its working elements.

The claimed invention is directed to solving the issue of direct combustion and gasification of finely dispersed organic substances, i.e. transforming the organic part of solid fuel into combustible gases during high-temperature heating with an oxidizing agent.

The technical result that can be obtained by carrying out the invention is the possibility of using various types of solid fuel (peat, oil shale, coal, industrial wastes, etc.) to produce heat and combustible gas, and the transition from the full combustion mode to the gas generation mode carried out by varying the air supply and maintaining the necessary moisture content of the original fuel.

The method of burning solid fuel, which consists in the fact that the combustion of finely dispersed fossil fuels is carried out in a cylindrical lined chamber, the lower part of which is a layer of sand on which discrete particles are deposited as regenerative elements, the fuel is uniformly fed to the combustion mirror, oxidizer (air) they are fed through rotating collectors fixed on the central axis into the layer between the sand and discrete particles, the fluidization of regenerative elements provides time characterized by the fact that the transition from the full fuel combustion mode to the gas generation mode is carried out by varying the air supply, thereby maintaining the temperature on the combustion mirror below the melting temperature of the ash, the resulting gas is burned up in the upper part of the chamber, while the carbon fuel burns out more fully in the mode gas generation provide the necessary moisture content of the original fuel.

In the gas generation mode, water vapor is required to improve the gas composition, while the presence of water for this type of fuel is provided by maintaining the necessary moisture content of the initial fuel.

The invention is illustrated by illustrations.

In FIG. 1 presents a device for implementing the proposed method, where:

1 - lined chamber;

2 - a layer of sand;

3 - discrete particles;

4 - the central axis;

5 - collectors;

6 - overflow threshold;

7 - capacity for collecting inert filling;

8 - air supply channels;

9 - supply of oxidizer (air) to the collectors;

10 - nozzle for supplying air for afterburning;

11 - fuel;

12 - channel for the removal of combustion products.

In FIG. Figure 2 shows schematically the process of interaction of the collector, a layer of sand and discrete particles that occurs during the movement of the collector and provides fluidization of discrete particles when air is supplied, where:

2 - a layer of sand;

3 - discrete particles;

5 - collector;

9 - air supply to the collectors.

The essence of the proposed method lies in the fact that the combustion and gasification of finely dispersed fossil fuels is carried out in a cylindrical lined chamber 1, the lower part of which is a layer of sand 2, on which discrete particles are poured into one layer 3. Fuel 11 is uniformly fed to the combustion mirror, oxidizer supply (air) is produced through channels 8 into rotating collectors 5 mounted on a central axis 4 into a layer between sand 2 and discrete particles 3. In this case, collectors 5 cause fluidization of di skretched particles. When the collectors 5 move, the particles behind the aft part of the collectors 5 press newly hit fuel particles against the sand layer 2, and conductive heat exchange occurs between the fuel 11 and the discrete particles 3, which in this case are regenerative elements, primarily heated by radiation from the lined walls of the cylindrical volume of the furnace . Water vapor and pyrolysis gas from the fuel 11 accumulate in the sand 2 under the discrete particles 3 since the porosity of the sand 2 is approximately 50%. The steam and pyrolysis gas accumulated in the steam volume are heated to a high temperature, and the pyrolysis gas serves as a source of ignition when air is supplied through the inclined surface of the next collector 5. The regenerative elements 3 integrated into the process provide significant intensification of the preparation of fuel particles for the combustion process. and the entire reaction process occurs in a thin layer of the combustion mirror, while the collectors 5 intersect each point of the combustion mirror repeatedly, providing chivaya thereby completeness response combustible components in each fuel particle (FIG. 2). The excess inert filling goes through the overflow threshold 6 into the tank 7 for collecting it.

In an embodiment of the gas generation process, the gas can be burned, if necessary, by additional air supply to the nozzle 10, the combustion products are discharged through the channel 12 located in the upper part of the lined combustion chamber.

The transition from the full fuel combustion mode to the gas generation mode is carried out by varying the air supply from α = 1.1-1.2 to α = 0.35-0.45 for this type of fuel, thereby maintaining the required temperature regime on the combustion mirror below the melting temperature ashes. Here α is the coefficient of excess air - the ratio of the actually spent air for fuel combustion to the theoretically necessary amount of air. The coefficient of excess air for each type of fuel is specified experimentally.

In the gas generation mode, to improve the composition of the gas, water vapor is required, which reacts with the carbon of the fuel, the amount of which can in some cases be supported by adding the right amount of water to the original fuel, i.e. the amount of water for this type of fuel is provided by maintaining the necessary moisture content of the original fuel.

The amount of steam introduced is approximately 0.4-0.5 kg per 1 kg of coke - part of the fuel entering the gasification zone. The temperature in the gasification zone is quite high. If the fuel contains a lot of moisture and part of it, together with coke, enters the gasification zone, then the amount of steam introduced is reduced. So, with gasification of peat w = 40-50%, water vapor can not be added to the introduced air or added in a minimum amount (see DB Ginsburg, Gasification of solid fuel, M., 1958, p. 23).

Consider an example of the use of the invention. For a stand-alone facility, it is required to generate up to 3 kW of electricity and up to 30 kW of heat. Fuel - brown coal fraction 0-2 mm with a calorific value of 17.6 MJ / kg. It is supposed to generate electricity using a system operating on generator gas: an internal combustion engine is an electric generator with an efficiency of 22%. Thus, the total net power of the system should be 3 / 0.22 + 30 = 43.6 or rounded 44 kW.

Generator gas is taken to generate electricity for cooling and purification from the bottom of the system. The gas going into the boiler is burned in the upper part of the chamber by supplying an additional air flow rate, bringing the air flow coefficient to 1.1. The entire gas generating part of the system operates with an air flow coefficient of 0.35. For low-power installations, the specific thermal voltage of the combustion mirror is taken to be 0.4 MW / m ² located at the bottom of its possible values, while the diameter of the combustion mirror and, accordingly, the diameter of the lined combustion chamber will be (44 / 0.4 × 10 ^{- 3} × 4 / π) ½ = 0.37 m. Assuming a 90% efficiency of the gas generation system, we obtain a fuel consumption of 44 × 3600 / (17.6 × 1000 × 0.9) = 10 kg / h.

Claims (1)

The method of burning fuel, which consists in the fact that the combustion of finely dispersed organic fuel is carried out in a lined chamber, the oxidizing agent is fed into the layer between the sand and discrete particles, the fluidization of regenerative elements is provided by rotating collectors, characterized in that the transition from the full combustion mode to the gas generation mode is carried out by varying air supply, maintaining the temperature on the combustion mirror below the melting temperature of the ash, burn the resulting gas in the upper part of the chamber, at this more complete burnout of the carbon fuel in the gas generation mode provide the maintenance of the necessary moisture content of the original fuel.

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